Performance Assessment of Laterite Concrete Modified with Nano-Silica Fines and Rice Husk Ash

Abstract

Aims: This study investigates the effect of partial substitution of 10% cement with varying compositions of nano-silica fines (NS) and rice husk ash (RHA) on the mechanical performance of laterite concrete. Methodology: Physical tests were performed on the constituent materials with reference to the British standards. Laterite was substituted for river sand by 30%; the batching was done by volume using a nominal mix ratio of 1:1.5:3 and a water/cement ratio of 0.6. Three ratios of NS/RHA were considered (3, 1, and 0.33) for the modification of the laterite concrete mix, and were tested for workability, compressive strength and water absorption to determine the optimal mixture. Results: The results show that laterite concrete modified with an NS/RHA ratio of 3 produced the highest 28-day compressive strength (17.991N/mm2) with adequate workability and water absorption. Notably, excessive RHA content led to lower compressive strength due to its lower reactivity. A 30% substitution of river sand with laterite resulted in a 19.13% drop in 28-day compressive strength; however, the modification of laterite concrete with NS/RHA ratios of 3, 1 and 0.33 led to strength changes of +24.18%, +6.433% and -7.124%, respectively, while maintaining sufficient workability (slump classes: S3 and S4) and water absorption (≤ 1.13%). Conclusion: The work highlights the potential of combining NS and RHA as an environmentally friendly solution for lowering cement usage, improving the strength of laterite concrete, promoting waste utilization, reducing reliance on river sand and promoting sustainability in construction works. The optimal NS/RHA ratio for 10% cement replacement was obtained as 3 and resulted in improved strength performance in laterite concrete.